The present invention generally relates to land clearing and to any operation involving mechanical vegetation cutting. More specifically, the present invention is concerned with a cutter head assembly for such operations.
Felling and mulching operations are conventionally performed using a removable cutter head fixed on a self-propelled vehicle that is either wheeled or tracked, for example. There are two types of equipment known in the art and readily available on the market for felling and mulching operations: vertical shaft cutter heads, usually mounted to the side of the vehicle, and horizontal shaft cutter heads, usually mounted to the front of the vehicle.
Vertical shaft cutter heads are generally similar to lawn mowers and will not be further discussed herein.
Horizontal shaft cutter heads are generally made of a horizontal rotor around which blades are attached by means of blade retaining devices. This rotor is typically driven in rotation by a hydraulic motor. The blade retaining devices are commonly made from long rods on which the blades are aligned out, side by side on the same row, or following a spiral design.
The cutter heads mentioned hereinabove have several drawbacks. More specifically, changing a single worn out blade can be complex and time-consuming. It often results in the user changing all the blades of a same row at once, no matter if they require being replaced or not, in order to avoid repeating the process within a short period of time and so as to prevent decreased cutting efficiency.
Moreover, the mechanical resistance of the above mentioned cutter heads to repeated impacts is limited because the rotor is generally made of a single hollow tube. Also, since the width of the rotor rarely exceeds 1.5 meters, the resulting cutting surface is insufficient for works on large terrains. This type of rotors is generally designed for domestic use more than for industrial applications.
In addition, the method of attachment of the cutter blades presented in the prior art does not satisfactorily meet the requirements of both simplicity and resistance to impacts. More precisely, the relatively wide interspaces provided between adjacent cutter blades, while enhancing the overall cutting surface of the device, may cause chips of wood or other foreign matters such as steel fence, roots, wire and the like, to be caught in these interspaces, which may reduce the efficiency of the cutter in use. Also, when performing cutting operation, such a design may result in projections of wood chips harmful to people standing around.
Efforts have been made in order to solve the above problems. In particular, the flail cutter described by Dallman, in his European Patent no. 0,951,815 issued in 1999, has a coaxial structure that comprises a rotation shaft inserted into a pair of hollow tubes. However, while permitting an easy set up of the cutter blade holding devices, this structure is not designed to sustain great impacts.
The prior art was also concerned with improving the shape of the cutter blade holders. Bachmans, in his patent GB 2,307,630 issued in 1997, describes an assembly comprising a hollow tube provided with apertures that receive cup-shaped elements welded by their bottom base to said tube. The walls of these elements extend beyond the diameter of the tube to form the cutter blade holders.
In spite of previous improvements, the mechanical resistance to impact of such assemblies is still often insufficient, and the design of the blade holders is not optimized in order to grant smooth unobstructed flow of the chipped wood and hence efficiency of the cutter head.
There is therefore a need for a cutter head that would be powerful, tough and safe enough to allow industrial work.
An object of the present invention is therefore to provide an improved cutter head assembly.
More specifically, in accordance with the present invention, there is provided a cutter head assembly comprising:
a first longitudinal member;
a second hollow longitudinal member provided with at least one aperture, said second longitudinal member being coaxial with said first longitudinal member and radially spaced apart therefrom;
at least one cup-shaped element comprising four side-walls, each said at least one cup-shaped element being fixedly mounted to both a corresponding one of said at least one aperture and said first longitudinal member; and
at least one cutter blade mounted in said at least one cup-shaped element.
According to another aspect of the present invention, there is provided a blade holder to removably secure a cutting blade into a generally longitudinal cutter head provided with a plurality of apertures separated by interspaces; said blade holder comprising:
a fin-shaped top surface;
a bottom surface to be mounted to said cutter head; and
lateral surfaces that are configured to receive a cutting blade;
wherein said blade holder has a longitudinal width that completely fills the interspace between two consecutive apertures of said cutter head.
Other objects, advantages and features of the present invention will become more apparent upon reading of the following nonrestrictive description of preferred embodiments thereof, given by way of example only with reference to the accompanying drawings.